Diamond rods inferior to CBN rods?

[Wanimator]

I will be receiving the diamond Sharpmaker rods, I keep hearing differing opinions about them vs the CBN rods, and I'm feeling like I'd gotten the wrong ones. Though I'm starting to doubt the validity of some of the diamond rod's shortcomings, given that I take my time, sharpen carefully and have a reasonable amount of experience with sharpening and sharpening with the Sharpmaker should I be worried about the diamond rods wearing out or chipping? Are the CBN rods really better? I sharpen LOTS of knives nearly on a daily basis varying from CPM-S30v, to T420 alloy to Aus-8 to carbon steels on a variety of knives so the longevity and potential chipping terrifies me for obvious reasons.

[Blerv]

As I understand they are both coexisting to see what people think and probably how they hold up relative to the diamonds as they are the current standard. If Sal & Co though they were inferior to the new CBN rods I feel they would quickly discontinue the diamonds as part of their CQI (constant quality improvement) methodology.

Regarding wear, I understand both the diamonds and cubic boron nitride are adhered in the same fashion and are MUCH harder than blade steel and even carbides. Assuming you are using light pressure and not dislodging the gems they should continue cutting in the same fashion as always. I would probably use a little water to avoid binding/hopping and cut down on the dust.

[Wanimator]

Regarding wear, I understand both the diamonds and cubic boron nitride are adhered in the same fashion and are MUCH harder than blade steel and even carbides. Assuming you are using light pressure and not dislodging the gems they should continue cutting in the same fashion as always. I would probably use a little water to avoid binding/hopping and cut down on the dust.

Yeah, that's what I thought. I imagine you'd have to be really misusing the rods to remove the abrasive gems, I don't use very much pressure or speed to begin with for consistency and to observe progress as best as possible. With as many steels from as many situations that I sharpen/repair I look forward to getting results on the diamonds and sharing them. (I want to acquire CBN rods at some point)

[Blerv]

Yeah, that's what I thought. I imagine you'd have to be really misusing the rods to remove the abrasive gems, I don't use very much pressure or speed to begin with for consistency and to observe progress as best as possible. With as many steels from as many situations that I sharpen/repair I look forward to getting results and sharing them.

Cool :). Looking forward to your results.

I recall in Cliff's testing he was impressed with the CBN's being able to perform on par with the diamonds. Not sure the exact results but I thought they were both very effective sharpening the most wear-resistant of steels.

[Cliff Stamp]

Are the CBN rods really better?

Just to clarify something, the only advantage to CBN over diamond is that CBN does better grinding ferrous materials because diamond can suffer wear through carbon diffusion. However this only happens under very high heat/pressure. At room temperature I have seen no data to indicate CBn is superior in both direct wear resistance and the bond strength is much more dependent on how they are bonding than the nature of CBN vs diamond.

The only suggestion I would make is to mark the sides and use one side until it stops cutting, this will allow you to keep track of the wear by the unused sides and eventually you can end up with three effective grits by just staging the wear. Of course always use lubricant and just the minimum force needed to cut.

[Wanimator]

Are the CBN rods really better?

Just to clarify something, the only advantage to CBN over diamond is that CBN does better grinding ferrous materials because diamond can suffer wear through carbon diffusion. However this only happens under very high heat/pressure. At room temperature I have seen no data to indicate CBn is superior in both direct wear resistance and the bond strength is much more dependent on how they are bonding than the nature of CBN vs diamond.

The only suggestion I would make is to mark the sides and use one side until it stops cutting, this will allow you to keep track of the wear by the unused sides and eventually you can end up with three effective grits by just staging the wear. Of course always use lubricant and just the minimum force needed to cut.

Thanks for the advice, I'll think about it. How "badly" do they (They being CBN and Diamond) actually wear? Some say they pretty much lose effectiveness on the corners quickly and then there's two sides to how the flats wear. One side says the flats work great for awhile then they break in and lose effectiveness, others say it's better after the break in. For you have they both worn differently I assume they wear the same because of bond strength pretty much dictating this.

One of the more regular uses for it will be sharpening everything from t-420 alloy, 440a, Chinese mystery steel, and other steels commonly found in kitchen knives.

[Cliff Stamp]

How "badly" do they (They being CBN and Diamond) actually wear?

They wear very slowly compared to alumina which is what is used to make the Spyderco medium/fine rods. They are not even in the same order of magnitude. CBN wears so slowly cutting steel compared to alumina on steel it is unlikely you would ever wear them out. How often do you hear people wearing out the medium rods and the CBN rods will wear 10-100 times slower. The only real concern is tearing the abrasive out which is why people often note issues with the corners as they are points of very high pressure.

The other unfortunate thing is that there is a very odd idea often suggested that you need to "break in" diamond/CBN abrasives so people often do fairly crazy things like rubbing them against each other which will rapidly degrade the abrasive. Or take the rods/stones and grind them against some kind of ceramic plate which also is likely to both rapidly wear the abrasive and tear it out if proper lubricant isn't used. When it gets torn out then you have chunks of CBN or diamond rolling around which rapidly degrade the rest of the abrasive.

I have threatened at times to do some kind of measurement but the problem is that the wear is so slow it would take a monumental amount of work to try to quantify it. I have diamond rods/plates which have ~20 years of use and tends of thousands of passes and they are still cutting fine. But again, you can damage them pretty easily if you use high force and no lubricant.

--

As an aside, for heavy work, a decent benchstone will be many times faster than the CBN rods :

-Sigma Power 120
-SPS-II 240
-Shapton Pro 220

are all decent choices.

[JD Spydo]

How "badly" do they (They being CBN and Diamond) actually wear?

They wear very slowly compared to alumina which is what is used to make the Spyderco medium/fine rods. They are not even in the same order of magnitude. CBN wears so slowly cutting steel compared to alumina on steel it is unlikely you would ever wear them out. How often do you hear people wearing out the medium rods and the CBN rods will wear 10-100 times slower. The only real concern is tearing the abrasive out which is why people often note issues with the corners as they are points of very high pressure.

Hey Cliff it's funny you happen to mention the gradual wear on a set of Spyderco's medium and fine alumina stones for the 204 Sharpmaker. I got one of the very first edition 204 Sharpmaker when they first put out on the open market. And GOD knows I've used the living **** out of both of my sets of 204 Sharpmaker kits. Well just today I've kind of determined that it's time to get myself a new set of the gray/medium stones for the 204 Sharpmaker. But first let me tell you all what kind of repetitive **** I've put this one set through before I had to replace them. I got this particular 204 Sharpmaker unit back in the late 90s/early 2000s and I've used this particular 204 Sharpmaker kit so much that I really should probably replace all the stones in it. But on further examination I can't find any significant wear on the white/fine alumina stones>> only the gray/medium really need to be changed out.

Now the set that I'm changing aren't total trash by any means and I plan on still using them on rough jobs and deburring jobs and so forth. But you can see significant wear on the corners so I thought I might just as well go ahead and order a new set just to keep the kit performing up to it's ultimate ability.

The point that I'm making coincides with what Cliff and others have been saying for a long time>> that is the alumina stones from the 204 Sharpmaker kit really can take some mean punishment before they need to be replaced. I mainly just want a new set of the medium/alumina stones for more precise corner work and better performance for sharpening various edges I use the corners of those stones for. Trust me you all will get many, many miles from those stones before you even notice any need for replacements.

[Cliff Stamp]

Trust me you all will get many, many miles from those stones before you even notice any need for replacements.

Just to clarify something, the Spyderco stones are solid abrasive, they don't ever wear out though the surface will eventually wear smooth. There is nothing preventing it from being reconditioned in the same way Norton India stones are reconditioned.

[Bodog]

I don't know how true it is, it could've been marketing gimmicks coming from a guy selling diamond or CBN stones. The guy said that there are, if I remember right, two types of diamonds used in sharpening stones. One has more microscopic edges leading to a reduced overall wear rate and increased abrasive properties. The other was smoother and wore out quicker because of the reduced points on the diamonds.

The guy said that CBN has the same structure as the better type of diamonds and that is the reason people may see better results with CBN than diamonds, because CBN has the same structure as the better diamonds with more than enough hardness to abrade all but the hardest materials. Add to the fact that CBN is cheaper than both types of diamonds and, again, according to the guy, there's no reason to go with any kind of diamond when any decently graded CBN is available. I won't mention the guy's name but he evidently deals in super high quality sharpening stones and emulsions.

I'll try to find it where this was said. Somewhere on bladeforums, I'm sure.

[Wanimator]

Hey Cliff it's funny you happen to mention the gradual wear on a set of Spyderco's medium and fine alumina stones for the 204 Sharpmaker. I got one of the very first edition 204 Sharpmaker when they first put out on the open market. And GOD knows I've used the living **** out of both of my sets of 204 Sharpmaker kits. Well just today I've kind of determined that it's time to get myself a new set of the gray/medium stones for the 204 Sharpmaker. But first let me tell you all what kind of repetitive **** I've put this one set through before I had to replace them. I got this particular 204 Sharpmaker unit back in the late 90s/early 2000s and I've used this particular 204 Sharpmaker kit so much that I really should probably replace all the stones in it. But on further examination I can't find any significant wear on the white/fine alumina stones>> only the gray/medium really need to be changed out.

That's interesting, this is not relevant to your case but in my experience the brown rods have actually gotten less "skippy" with use but just as abrasive, and provides a smoother edge than what they would when new (perhaps that's experience with the edge it produces) I am careful with the corners and don't have a decade of use in them so I can't speak about the corners becoming less acute.

I don't know how true it is, it could've been marketing gimmicks coming from a guy selling diamond or CBN stones. The guy said that there are, if I remember right, two types of diamonds used in sharpening stones. One has more microscopic edges leading to a reduced overall wear rate and increased abrasive properties. The other was smoother and wore out quicker because of the reduced points on the diamonds.

The guy said that CBN has the same structure as the better type of diamonds and that is the reason people may see better results with CBN than diamonds, because CBN has the same structure as the better diamonds with more than enough hardness to abrade all but the hardest materials. Add to the fact that CBN is cheaper than both types of diamonds and, again, according to the guy, there's no reason to go with any kind of diamond when any decently graded CBN is available. I won't mention the guy's name but he evidently deals in super high quality sharpening stones and emulsions.

I'll try to find it where this was said. Somewhere on bladeforums, I'm sure.

I look forward to seeing it, those are some "interesting" claims, although I can be quite skeptical about sales pitches.

[Bodog]

I wasn't entirely accurate:

"There are three types of diamond:

Monocrystalline Diamond (MDP)
Polycrystalline Diamond (PDP)
Natural Diamond (NDP)

So whats the difference?

Monocrystalline diamond is cheap to produce (relatively speaking) and its still diamond. Making it quick to cut even the most ridiculous of steels and even ceramics. However it has a blocky shape with few cutting edges. This makes it slower than other diamond types but at less than half the cost to produce its a even tradeoff for things such as diamond plates and films.


Polycrystalline diamond is quite expensive to produce , and as a result is often overlooked when discussing sharpening abrasives. However it has many times the number of cutting edges than Monocrystalline and Natural Diamonds. This results in faster cutting. I find it also leaves a "stickier" edge when compared side by side to monocrystalline preparations.



Natural Diamond is not discussed at all for sharpening , in fact I don't know of anyone who has used the stuff to sharpen with. It is quite costly even more so than Polycrystalline and does not offer any advantages over Polycrystalline , but does however have more cutting edges than Monocrystalline. I also suspect that a Natural Diamond prepration would have a poorer particle size distribution compared to the other variants. Typically Natural Diamond is used in the gem/diamond polishing markets but it is also used for general lapping and polishing applications. Larger crystal NDP is used for single point tool applications and in some cases for diamond die applications.



So if you have read thus far you may be wondering where Cubic Boron Nitride (CBN) falls into all of this. CBN has a polycrystalline structure , meaning it has more cutting surfaces (comparing equally sized particles remember) , than its Monocrystalline and even Natural Diamond counterparts. It falls in between Monocrystalline and Polycrystalline diamond for cost , and poses a close second to Polycrystalline in terms of performance. CBN is the second hardest substance (next to diamond) and is harder than diamond in high temperature applications. Allowing it to cut even vanadium rich steels with ease.


So why don't we see sharpening stones with CBN mixed in? Because you can just add a drop of a CBN stropping compound onto your waterstone to enhance its performance and allow it to cut even the most exotic steels with ease.

For more information about PDP , MDP , CBN and particle size distribution , check out this this blog.
http://www.precisesharpening.blogspo...e-quarter.html" onclick="window.open(this.href);return false;"

Screw it, I'll say it, the dude likely got most of this information from Ken Schwartz, for whatever that may mean to you guys.

Right, wrong, or indifferent, there are a couple of pretty cool photos in the thread.

http://www.bladeforums.com/forums/showt ... on+nitride" onclick="window.open(this.href);return false;

[Bodog]

.....

[Cliff Stamp]

[quoting some external source]

So why don't we see sharpening stones with CBN mixed in?

Because it would be silly to do so as it would be inferior to diamond and significantly more expensive (CBN is >> costly than synthetic diamond).

[Bodog]

[quoting some external source]

So why don't we see sharpening stones with CBN mixed in?

Because it would be silly to do so as it would be inferior to diamond and significantly more expensive (CBN is >> costly than synthetic diamond).

Hey man, I'm just quoting someone who sounds like he's saying something legitimate. I have no idea if there are monocrystalline or polycrystalline diamonds and where CBN falls. The guy said something that makes sense on the surface so I brought it up because I thought it may add to the discussion. Feel free to refute it, but don't aim at me.

[Cliff Stamp]

Feel free to refute it, but don't aim at me.

I noted you were referencing an external source in the response, almost guaranteed to be someone selling CBN or quoting someone who does.

[Bodog]

Feel free to refute it, but don't aim at me.

I noted you were referencing an external source in the response, almost guaranteed to be someone selling CBN or quoting someone who does.

Yeah, that's what I said when I posted it. Are you going to refute it or simply call the person a shill? I do not know enough about those products to refute or validate what was said by the other person, I can only say that it makes some sense. You cannot invalidate something just because someone is trying to sell it. That's like saying someone is a shill when they say pocket clips on knives help keep a knife clipped to a pocket and then try to sell a knife with a pocket clip. Is that invalid?

[tvenuto]

Yeah, that's what I said when I posted it. Are you going to refute it or simply call the person a shill? I do not know enough about those products to refute or validate what was said by the other person, I can only say that it makes some sense. You cannot invalidate something just because someone is trying to sell it. That's like saying someone is a shill when they say pocket clips on knives help keep a knife clipped to a pocket and then try to sell a knife with a pocket clip. Is that invalid?

...and this is where threads like this go sideways. This response is completely out of proportion with Cliffs statement to you. He gave a reason that it would be silly, and that reason was not because someone was trying to sell it. The word shill was never mentioned, perhaps you misread the word silly? Your pocket clip example is not analogous to any situation that's been discussed in this thread.

[JD Spydo]

Trust me you all will get many, many miles from those stones before you even notice any need for replacements.

Just to clarify something, the Spyderco stones are solid abrasive, they don't ever wear out though the surface will eventually wear smooth. There is nothing preventing it from being reconditioned in the same way Norton India stones are reconditioned.

The only thing wrong with these medium-gray 204 Sharpmaker stones is that the corners do have some significant wear on them. They are literally rounded off to a degree to where they don't have that well defined corner that I like to do detail work with. But considering I've had and used these stones for well over 14 years and used them hard I'm not at all complaining.

Also I do remember one Brother about a year or so ago that claimed his medium/gray Spyderco 302 Benchstone dished out on him. I'm 100% sure you're absolutely right about those stones being repairable but with the time I would have to spend on them it doesn't bother me to shell out $30+ to get a perfect/new set of them.

Now I've never heard of anyone wearing out the fine or Ultra-fine Spyderco stones ever. But over the years I've heard of at least 3 to 4 times where people have chimed in with problems on the Spyderco medium/gray stones.

Now you got me curious?? what tools would you use to make these medium/gray 204 Sharpmaker stones good again?

[Cliff Stamp]

Now you got me curious?? what tools would you use to make these medium/gray 204 Sharpmaker stones good again?

A harder abrasive, either a super abrasive like diamond/CBN or silicon carbide in a very weak bond (or loose grit). You have to take care when using silicon carbide as while it is harder than alumina it is only just harder and will wear rapidly against the Sharpmaker rods (or benchstones) from Spyderco. You need a soft bond stone to ensure that fresh grit is released or else you can just end up polishing the stones even more. Sandpaper is also an option, but again take care to not continue using the sandpaper when it is worn. Take silicon carbide, ideally just slightly less in grit than the stone you are trying to condition.

If you want to experiment you might want to start with a Norton India because a near identical process is used but it is much easier on the Norton as they are not solid abrasive (they are vitrified bonded) and so they condition easier. A lot of people never do that and so they never experience how Norton stones can actually cut as they only use them in the worn condition where all of the abrasive is rounded/worn.